Apparatus for determining the relative density of two gases



Jan. 30, 1923.

R. F. MACMICHAELn APPARATUS FoR DETERMINING TI-IE RELATIVE DENSITY oF Two GASES.

FILED Nov. 27-, 1920.

2 SHEETS-SHEET I Mr enen- R' F- MACMICHAELl APPARATUS FOR DETERMINlNG THE RELATlvE DENSITY oF Two GASES.

FlLED Nov. 27, 1920. 2 SHEETS-SHEET 2 Patented Jan. 30, 1923.

UNITED STATES PATENT OFFICE.

ROSS F. MACMICHAEL, OF'CHICAGO, ILLINOIS; ADELOR J. PETIT, JR., ADMINISTRATOR F SAID ROSS F. MACMICHAEL, DECEASED.

APPARATUS FOR DETERMINING THEIRELATIVE DENSITY 0F TWO GASES.

Application filed November 27, 1920. Serial No. 426,730.

To all whom it may concern,

Be it kno-wn that I, Ross F'. MACMIGHAEL, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Apparatus for Determining the Relative Density of Two Gases, of which the following is a full, clear,

concise, and exact description, reference being had to the accompanying drawings,

forming a part of this specification.

This invention relates to improvements in apparatus for determining the relative density of two vases by means of centrifugal force. The oiject is to provide a rapid, ac-

curate and dependable apparatus for this purpose with particular reference to determining the CO2 content of flue gases.

In the drawing Figure 1 is a general elevation of the machine as used in a power p-lant. Figure 2 is a partial vertical section showing the speed control device, Figure 3 being a plan view of same. l1 igure 4 shows aA characteristic curve of the fans used. Figure '5 is a top plan View of the machine. Figure 6 is a partial sectional elevation along the broken line A-B of Figure 5, some parts being distorted in the conventional manner to show the construction-more clearly. Figure 7 is a similar view along the broken line C-D of Figure 5. Figure 8 is a artial side elevation.

n the drawing 1 is a flue. 2 is a gas sainple pipe extending into the flue in the usual manner. 3 is a. filtering, cooling and humidifying device. 4 is a rotor combinin a steam turbine 53, a gas fan 49 and an air Ian 51 in an integral member. 5 is a speed control device to maintain constant suction on the air fan. 6 is an indicating differential draft gage aduated in C02. 7 is a recording di erential draft gage graduated for CO2.

In operation a sample of gas is withdrawn from the fiue 1 thru pipe This passes down thru filter 8, which is removable for cleaning by means of taperjoint 9 and felt plug 10. Filter 8 is composed of bristles,

y cotton strings, or other sim1lar material, 5o mounted on twisted wire 11. Wire 11 is also attached to felt plug 10, which permits a slow seepage of water into chamber l12. The water and gas mixed pass up thru tube 13 in vspray form or after the manner of an air lift pump, separating in chamber 14. The water passes out thru opening 15v down thru'tube .16 to main reservoir 17. The seepage of water through plug 10 is very slow and the quantity of water in contact with the gas is small to reduce the effect of absorption.

The gas in its passage thru tube 13 is humiditied and brought to the desired temperature by the surrounding water 18 which is circulated as later described. The as in 14 is under a variable suction depending on the draft in the flue, the condition of the iilter etc, of say 6 or 8 inches of water. From 14 it passes thru orifice 19 and tube 2() to gas fan chamber 21, thence out thru gas fan 49 and the annular opening 50 to the atmosphere through shield 45.

A sample of air is taken in thru opening 22, passing down thru tube 23 which acts as a restricting orifice. At 24 it meets a stream of water drawn up thru hose 25 from the bottom of the reservoir 17, and the air and water mixed pass up thru tube 26, separating in chamber 27 thelwater passin downward again to the reservoir. The ead of water in the chamber 18 is maintained by the suction in chamber 27 which is due to the pull of the fan and is regulated by the reysufiicient to humidify the air and bring the air and gas samples to the desired temperature. Air in chamber 27 under a suction of say 6 o-r 8 inches of water as noted above passes thru orifice 28, thru tube 29 into air fan chamber 30, thence thru air fan 51 and annular opening 52 and shield 45 tothe atmosphere.

For rapid indication of changes in the constitution, of the flue gas, it is desirable that a high velocity be maintained in pipe 2, which requires a relatively large volume of gas to be handled by the fan. On the other hand, to prevent flooding the fan and destroying the suction which it is desired to maintain in chamber 21, it is necessarv that the volume of gas handled be held down to a small fraction of the total capacity of the fan. Therefore the machine parts. are so proportioned as to secure the best conditions taking into view both of the above considera.

` tions.l The orifices 15 and 28 limit the amount of as. which passes to the fan.

U tube 33 is illed with water to the level of the overflow opening 34 while the machine is not operating. When operation coml mences .suction in chamber 31, increases, re-

' ducing the water level at 35 till iioat 36 falls.

This operates lever 37 raising baille 38 which partially intercepts ysteam jet from nozzle 61. This reduces the speed or the turbine till the suction in chamber falls to slightly below normal, when the process is reversed. These slight fluctuations above and below normal maintain the average suction on the air side at the desired point. Float 36 and lever 37 are readil removable by rotating the top piece39 andy lifting the float out of the U tube.

Suctionk in the chamber 21 will vary directly as the density of the gas being tested.

Suction is transmitted to pipes 40 and 41 respectively, and thence to ga es 6 and 7, which show the per cent of C 2 in the flue gas directly.

Flue gas containing 21% CO2 has a density about 9% higher than air. Therefore if a suction of about 47 inches of water is Y make this clear.

maintained on the airside, 1% of CO2 will show about'0.2 inchl of water on the gages, which is ample for any purposes of indicating, recording or control.

The function of the orice 28 is to increase the suction to' a suitable working point and eliminate the efect of variations in suction in chamber 27. This is ei'ected by allowing a variable'quantity of air to pass thru the orifice to the'fan. A numerical example will Suction in air fan 30 is maintained constant at 47 inchesof water, as described above. Assumea suction in chamber 27 of 6 inches, then the drop thru the orilice 28 and tube 29 will be 41 inches. The

iow will be'proportional to the square root of this drop or 6.40.

Assume that the suction in 27 increases to 8 inches. The drop thru the orifice and tube now amounts to 39 inches since the 47 inches is held constant. The How will now be pro- Iortional to the square root of 39 or 6.25. his shows a decrease of about 24%. Referring to Figure 4 the fan is proportioned so that the actual operating point' is far baclcon the flat part of the curve, as at 42. Atp/this point a variation of 25% in volume would ave no appreciable effect on the suction, even without a change of speed to compensate as could occur when the air side is considered.

A .similar line of reasoning applies to the gas side 'to take care of variations in the flue spectively. The steam jet and exhaust may also be enclosed in a shield 45 discharging into the atmosphere. Heating of the fans by conduction from the turbine buckets in the periphery ofthe rotor may be reduced by a circulation of air in thru openings 46, discharging out thru shield 45 to the atmosphere. This air flow is induced by the friction of the rotor. The discharge from the fans also passes outward in a similar manner. A slight heating of the fans is of no consequence provided it is uniform on both sides.

Casing 47 maintains the water level in `reservoir 17, surplus water discharging out thru drain 48.

It is evident that many modifications are possible without departing from the spirit of the invention. Thus for marine work where water columns are unsuitable, spring diaphragms may be substituted. Electric drive may be used where desired, either directly thru gears or shaft connection, or indirectly to operate anvair blower to supply air for the turbine, the latter requiring "no change in construction of the machine proper. Compressed air from any lixed source of supply may also be used for operation.

The apparatus described furnishes ameans for determinin the density of flue gases with great rapidity and with a suflicient degree of accuracy for practical purposes. Indicators and recorders graduated for CO2 ive a continuous record practically free rom lag.` They may also be placed in any desired location.

Control apparatus' and si als are also readily operated by means o this machine. As no chemicals are used, and as the entire apparatus is a simple mechanical dlevice readily understood and operated by power plant attendants, it is particularly adapted for this class of service.

Having described my invention I claim 1. In an apparatus for comparing the density of two gases, a source of supply for each gas, means for bringing the gases to uni- 3. In a machine for analyzing gas, a rotor havinga central disk carryin a turbine at its perlphery, two adjacent ans on either l side of the disk, and two bearings adjacent to the fans.

4. In a machine for analyzing gas, two fans having very Hat pressure-volume curves at the operating point. Y

5. In a machine for analyzin gas, a pressure control consisting of a U tu containing a liquid, one legof which is subjected to gas pressure, and the other leg of which contains a float adapted to operate aspeed control device.

6. In a machine for analyzing gas, means for humidifying the gases by introducing water into the gas streams and means for removing the surplus water. 1

7. In a machine for analyzing gas, means for bringing two gases to equal conditions of temperature, including a body of water, and means for circulating such temperature regulating water bythe action of both of vthe gases.

8. In a machine for analyzing gases, two fans rotated at the same speed, means for bringing two gases to the same temperature, and means for maintaining a constant Suction on one of the fans.

9. In a machine for analyzing gases, a suction means for each gas' all operated at the same speed, orifices through which the lgases are passed to the suction means, said suction means being so proportioned to the capacity of the orifices thatlthe proper proportions of velocities to pressure are maintalned.

l0. 'In a machine for analyzing gases, suction means for the different gases including a plurality of fans all operated at the same speed, orifices through which the gases are passed to the fans, the capacity of said fans being so proportioned to the capacity of the orifices that the proper proportions of velocities to pressure are maintained- 11. In an apparatus for analyzin gases, the combination of suction means, a c amber directly connected with such suction means,

means connectin said chamber to a temperature and humidlty regulating device, means formaintaining the temperature in said suction chamber constant, and alow regulating orifice between said suction means and the temperature and humidity regulating means. In witness whereof, I hereunto subscribe my name this 24th day of November, 1920.

ROSS F. MACMICHAEL. 

